Method and apparatus for determining longevity

ABSTRACT

A method and apparatus for determining estimated remaining longevity for an implantable stimulator. A programmer processor is employed to acquire from the implantable stimulator a signal comprising data associated with the power source in the implantable stimulator and a date in which the stimulator was implanted. The programmer processor and the data are used to determine whether a pre-recommended replacement time threshold (pre-RRT) has been attained for replacing the implantable stimulator. The programmer processor is used to select an equation in which to calculate a recommended replacement time (RRT), the equation is selected in response to determining a time period that extends from the date in which the stimulator was implanted until a date in which the pre-RRT is attained.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims the benefit of U.S. Patent application Ser. No.62/084,898 filed on Nov. 26, 2014. The disclosure of theabove-referenced application is incorporated herein by reference in itsentirety.

TECHNICAL FIELD

This disclosure relates to implantable medical devices and, moreparticularly, to implantable medical devices.

BACKGROUND

A variety of medical devices for delivering a therapy and/or monitoringa physiological condition have been used clinically or proposed forclinical use in patients. Examples include medical devices that delivertherapy to and/or monitor conditions associated with the heart, muscle,nerve, brain, stomach or other organs or tissue. Some therapies includethe delivery of electrical signals, e.g., stimulation, to such organs ortissues. Some medical devices may employ one or more elongatedelectrical leads carrying electrodes for the delivery of therapeuticelectrical signals to such organs or tissues, electrodes for sensingintrinsic electrical signals within the patient, which may be generatedby such organs or tissue, and/or other sensors for sensing physiologicalparameters of a patient. Some medical devices may be “leadless” andinclude one or more electrodes on an outer housing of the medical deviceto deliver therapeutic electrical signals to organs or tissues and/orsense intrinsic electrical signals or physiological parameters of apatient.

Medical leads may be configured to allow electrodes or other sensors tobe positioned at desired locations for delivery of therapeuticelectrical signals or sensing. For example, electrodes or sensors may becarried at a distal portion of a lead. A proximal portion of the leadmay be coupled to a medical device housing, which may contain circuitrysuch as signal generation and/or sensing circuitry. In some cases, themedical leads and the medical device housing are implantable within thepatient, while in other cases percutaneous leads may be implanted andconnected to a medical device housing outside of the patient. Medicaldevices with a housing configured for implantation within the patientmay be referred to as implantable medical devices. Leadless medicaldevices are typically implantable medical devices positioned within oradjacent to organs or tissues within a patient for delivery oftherapeutic electrical signals or sensing. In some example, leadlessimplantable medical devices may be anchored to a wall of an organ or totissue via a fixation mechanism.

Implantable cardiac pacemakers or cardioverter-defibrillators, forexample, provide therapeutic electrical signals to the heart, e.g., viaelectrodes carried by one or more medical leads or via electrodes on anouter housing of a leadless implantable medical device. The therapeuticelectrical signals may include pulses for pacing, or shocks forcardioversion or defibrillation. In some cases, a medical device maysense intrinsic depolarizations of the heart, and control delivery oftherapeutic signals to the heart based on the sensed depolarizations.Upon detection of an abnormal rhythm, such as bradycardia, tachycardiaor fibrillation, an appropriate therapeutic electrical signal or signalsmay be delivered to restore or maintain a more normal rhythm. Forexample, in some cases, an implantable medical device may deliver pacingstimulation to the heart of the patient upon detecting tachycardia orbradycardia, and deliver cardioversion or defibrillation shocks to theheart upon detecting fibrillation.

In general, implantable medical devices require a small housing formfactor to enable an unobtrusive implantation within a patient. In thecase of leadless implantable medical devices, the housing form factormust be extremely small to enable implantation within or adjacent toorgans or tissue. For example, a leadless pacemaker may be implanteddirectly into a ventricle of the heart. Battery usage is always aconcern when designing implantable medical devices, but this concern isincreased for small form factor devices that can only accommodate asmall battery canister.

SUMMARY

The details of one or more aspects of the disclosure are set forth inthe accompanying drawings and the description below. Other features,objects, and advantages of the disclosure will be apparent from thedescription and drawings, and from the claims.

The present disclosure determines estimated remaining longevity for animplantable stimulator having a power source and processor. Theprocessor acquires data associated with the power source in theimplantable stimulator and a date in which the stimulator was implanted.The processor uses the data to determine whether a pre-recommendedreplacement time threshold (pre-RRT) has been attained for replacing theimplantable stimulator. The processor selects an equation in which tocalculate a recommended replacement time (RRT). The equation is selectedin response to determining a time period that extends from the date inwhich the stimulator was implanted until a date in which the pre-RRT isattained.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a diagram illustrating an example therapy system comprising aleadless implantable medical device (IMD) that may be used to monitorone or more physiological parameters of a patient and/or provide therapyto the heart of a patient.

FIG. 2 is a diagram illustrating another example therapy systemcomprising an IMD coupled to a plurality of leads that may be used tomonitor one or more physiological parameters of a patient and/or providetherapy to the heart of a patient.

FIG. 3 illustrates the IMD of FIG. 1 in more detail.

FIG. 4 illustrates the IMD of FIG. 2 in more detail.

FIG. 5 is a functional block diagram illustrating an exampleconfiguration of an IMD.

FIG. 6 is a block diagram of an example external programmer thatfacilitates user communication with an IMD.

FIG. 7 is a block diagram illustrating an example system that includesan external device, such as a server, and one or more computing devicesthat are coupled to an IMD and programmer via a network.

The inter-relation of defined events related to the invention isillustrated in FIG. 8.

The times of occurrences of these defined events relative to anexemplary battery discharge curve is illustrated in FIG. 9.

FIG. 10 is a table illustrating an exemplary mechanism by which thepresent invention calculates estimated remaining battery life (RemainingLongevity Duration Value) in days.

FIG. 11 is a battery discharge curve depicting pre-recommendedreplacement time (RRT) that is set in order to extend the life of abattery.

FIG. 12 is a graphical user interface depicting the actual date abattery must be replaced.

DETAILED DESCRIPTION

FIG. 1 is a diagram illustrating an exemplary therapy system 10A thatmay be used to monitor one or more physiological parameters of patient14 and/or to provide therapy to heart 12 of patient 14. Therapy system10A includes an implantable medical device (IMD) 16A, which is coupledto programmer 24. IMD 16A may be an implantable leadless pacemaker thatprovides electrical signals to heart 12 via one or more electrodes (notshown in FIG. 1) on its outer housing. Additionally or alternatively,IMD 16A may sense electrical signals attendant to the depolarization andrepolarization of heart 12 via electrodes on its outer housing. In someexamples, IMD 16A provides pacing pulses to heart 12 based on theelectrical signals sensed within heart 12. Patient 14 is ordinarily, butnot necessarily, a human patient.

In the example of FIG. 1, IMD 16A is positioned wholly within heart 12with one end proximate to the apex of right ventricle 28 to provideright ventricular (RV) pacing. Although IMD 16A is shown within heart 12and proximate to the apex of right ventricle 28 in the example of FIG.1, IMD 16A may be positioned at any other location outside or withinheart 12. For example, IMD 16A may be positioned outside or within rightatrium 26, left atrium 36, and/or left ventricle 32, e.g., to provideright atrial, left atrial, and left ventricular pacing, respectively.Depending in the location of implant, IMD 16A may include otherstimulation functionalities. For example, IMD 16A may provideatrioventricular nodal stimulation, fat pad stimulation, vagalstimulation, or other types of neurostimulation. In other examples, IMD16A may be a monitor that senses one or more parameters of heart 12 andmay not provide any stimulation functionality. In some examples, system10A may include a plurality of leadless IMDs 16A, e.g., to providestimulation and/or sensing at a variety of locations.

FIG. 1 further depicts programmer 24 in communication with IMD 16A. Insome examples, programmer 24 comprises a handheld computing device,computer workstation, or networked computing device. Programmer 24includes a user interface that presents information to and receivesinput from a user. It should be noted that the user may also interactwith programmer 24 remotely via a networked computing device.

A user, such as a physician, technician, surgeon, electrophysiologist,other clinician, or patient, interacts with programmer 24 to communicatewith IMD 16A. For example, the user may interact with programmer 24 toretrieve physiological or diagnostic information from IMD 16A. A usermay also interact with programmer 24 to program IMD 16A, e.g., selectvalues for operational parameters of the IMD 16A. For example, the usermay use programmer 24 to retrieve information from IMD 16A regarding therhythm of heart 12, trends therein over time, or arrhythmic episodes.

As another example, the user may use programmer 24 to retrieveinformation from IMD 16A regarding other sensed physiological parametersof patient 14 or information derived from sensed physiologicalparameters, such intracardiac or intravascular pressure, activity,posture, respiration, tissue perfusion, heart sounds, cardiacelectrogram (EGM), intracardiac impedance, or thoracic impedance. Insome examples, the user may use programmer 24 to retrieve informationfrom IMD 16A regarding the performance or integrity of IMD 16A or othercomponents of system 10A, or a power source of IMD 16A. As anotherexample, the user may interact with programmer 24 to program, e.g.,select parameters for, therapies provided by IMD 16A, such as pacingand, optionally, neurostimulation.

IMD 16A and programmer 24 may communicate via wireless communicationusing any techniques known in the art. Examples of communicationtechniques may include, for example, low frequency or radiofrequency(RF) telemetry, but other techniques are also contemplated. In someexamples, programmer 24 may include a programming head that may beplaced proximate to the patient's body near the IMD 16A implant site inorder to improve the quality or security of communication between IMD16A and programmer 24.

FIG. 2 is a diagram illustrating another exemplary therapy system 10Bthat may be used to monitor one or more physiological parameters ofpatient 14 and/or to provide therapy to heart 12 of patient 14. Therapysystem 10B includes IMD 16B, which is coupled to leads 18, 20, and 22,and programmer 24. In one example, IMD 16B may be an implantablepacemaker that provides electrical signals to heart 12 via electrodescoupled to one or more of leads 18, 20, and 22. In addition to pacingtherapy, IMD 16B may deliver neurostimulation signals. In some examples,IMD 16B may also include cardioversion and/or defibrillationfunctionalities. In other examples, IMD 16B may not provide anystimulation functionalities and, instead, may be a dedicated monitoringdevice. Patient 14 is ordinarily, but not necessarily, a human patient.

Leads 18, 20, 22 extend into the heart 12 of patient 14 to senseelectrical activity of heart 12 and/or deliver electrical stimulation toheart 12. In the example shown in FIG. 2, right ventricular (RV) lead 18extends through one or more veins (not shown), the superior vena cava(not shown), right atrium 26, and into right ventricle 28. RV lead 18may be used to deliver RV pacing to heart 12. Left ventricular (LV) lead20 extends through one or more veins, the vena cava, right atrium 26,and into the coronary sinus 30 to a region adjacent to the free wall ofleft ventricle 32 of heart 12. LV lead 20 may be used to deliver LVpacing to heart 12. Right atrial (RA) lead 22 extends through one ormore veins and the vena cava, and into the right atrium 26 of heart 12.RA lead 22 may be used to deliver RA pacing to heart 12.

In some examples, system 10B may additionally or alternatively includeone or more leads or lead segments (not shown in FIG. 2) that deploy oneor more electrodes within the vena cava or other vein, or within or nearthe aorta. Furthermore, in another example, system 10B may additionallyor alternatively include one or more additional intravenous orextravascular leads or lead segments that deploy one or more electrodesepicardially, e.g., near an epicardial fat pad, or proximate to thevagus nerve. In other examples, system 10B need not include one ofventricular leads 18 and 20.

IMD 16B may sense electrical signals attendant to the depolarization andrepolarization of heart 12 via electrodes (described in further detailwith respect to FIG. 4) coupled to at least one of the leads 18, 20, 22.In some examples, IMD 16B provides pacing pulses to heart 12 based onthe electrical signals sensed within heart 12. The configurations ofelectrodes used by IMD 16B for sensing and pacing may be unipolar orbipolar.

IMD 16B may also provide neurostimulation therapy, defibrillationtherapy and/or cardioversion therapy via electrodes located on at leastone of the leads 18, 20, 22. For example, IMD 16B may deliverdefibrillation therapy to heart 12 in the form of electrical pulses upondetecting ventricular fibrillation of ventricles 28 and 32. In someexamples, IMD 16B may be programmed to deliver a progression oftherapies, e.g., pulses with increasing energy levels, until afibrillation of heart 12 is stopped. As another example, IMD 16B maydeliver cardioversion or ATP in response to detecting ventriculartachycardia, such as tachycardia of ventricles 28 and 32.

As described above with respect to IMD 16A of FIG. 1, programmer 24 mayalso be used to communicate with IMD 16B. In addition to the functionsdescribed with respect to IMD 16A of FIG. 1, a user may use programmer24 to retrieve information from IMD 16B regarding the performance orintegrity of leads 18, 20 and 22 and may interact with programmer 24 toprogram, e.g., select parameters for, any additional therapies providedby IMD 16B, such as cardioversion and/or defibrillation.

In addition to the functions described with respect to IMD 16A of FIG.1, a user may use programmer 24 to retrieve information from IMD 16Bregarding the performance or integrity of leads 18, 20 and 22 and mayinteract with programmer 24 to program, e.g., select parameters for, anyadditional therapies provided by IMD 16B, such as cardioversion and/ordefibrillation.

FIG. 3 is a diagram illustrating leadless IMD 16 of FIG. 1 in furtherdetail. In the example of FIG. 3, leadless IMD 16A includes fixationmechanism 70. Fixation mechanism 70 may anchor leadless IMD 16A to awall of heart 12. For example, fixation mechanism 70 may take the formof multiple tines that may be inserted into a wall of heart 12 to fixleadless IMD 16A at the apex of right ventricle 28. Alternatively, otherstructures of fixation mechanism 70, e.g., adhesive, sutures, or screwsmay be utilized. In some examples, fixation mechanism is conductive andmay be used as an electrode, e.g., to deliver therapeutic electricalsignals to heart 12 and/or sense intrinsic depolarizations of heart 12.

Leadless IMD 16A may also include electrodes 72 and 74 at a tip of outerhousing 78. Electrodes 72 and 74 may be used to deliver therapeuticelectrical signals to heart 12 and/or sense intrinsic depolarizations ofheart 12. Electrodes 72 and 74 may be formed integrally with an outersurface of hermetically-sealed housing 78 of IMD 16A or otherwisecoupled to housing 78. In this manner, electrodes 72 and 74 may bereferred to as housing electrodes. In some examples, housing electrodes72 and 74 are defined by uninsulated portions of an outward facingportion of housing 78 of IMD 16A. Other division between insulated anduninsulated portions of housing 78 may be employed to define a differentnumber or configuration of housing electrodes. For example, in analternative configuration, IMD 16A may include a single housingelectrode that comprises substantially all of housing 78, and may beused in combination with an electrode formed by fixation mechanism 70for sensing and/or delivery of therapy.

FIG. 4 is a diagram illustrating IMD 16B and leads 18, 20, 22 of therapysystem 10B of FIG. 2 in greater detail. Leads 18, 20, 22 may beelectrically coupled to a signal generator and a sensing module of IMD16B via connector block 34. In some examples, proximal ends of leads 18,20, 22 may include electrical contacts that electrically couple torespective electrical contacts within connector block 34 of IMD 16B. Insome examples, a single connector, e.g., an IS-4 or DF-4 connector, mayconnect multiple electrical contacts to connector block 34. In addition,in some examples, leads 18, 20, 22 may be mechanically coupled toconnector block 34 with the aid of set screws, connection pins, snapconnectors, or another suitable mechanical coupling mechanism.

Each of the leads 18, 20, 22 includes an elongated insulative lead body,which may carry a number of concentric coiled conductors separated fromone another by tubular insulative sheaths. Bipolar electrodes 40 and 42are located adjacent to a distal end of lead 18 in right ventricle 28.In addition, bipolar electrodes 44 and 46 are located adjacent to adistal end of lead 20 in left ventricle 32 and bipolar electrodes 48 and50 are located adjacent to a distal end of lead 22 in right atrium 26.In the illustrated example, there are no electrodes located in leftatrium 36. However, other examples may include electrodes in left atrium36.

Electrodes 40, 44, and 48 may take the form of ring electrodes, andelectrodes 42, 46, and 50 may take the form of extendable helix tipelectrodes mounted retractably within insulative electrode heads 52, 54,and 56, respectively. In some examples, one or more of electrodes 42,46, and 50 may take the form of pre-exposed helix tip electrodes. Inother examples, one or more of electrodes 42, 46, and 50 may take theform of small circular electrodes at the tip of a tined lead or otherfixation element. Leads 18, 20, 22 also include elongated electrodes 62,64, 66, respectively, which may take the form of a coil. Each of theelectrodes 40, 42, 44, 46, 48, 50, 62, 64, and 66 may be electricallycoupled to a respective one of the coiled conductors within the leadbody of its associated lead 18, 20, 22, and thereby coupled torespective ones of the electrical contacts on the proximal end of leads18, 20, 22.

In some examples, as illustrated in FIG. 4, IMD 16B includes one or morehousing electrodes, such as housing electrode 58, which may be formedintegrally with an outer surface of hermetically-sealed housing 60 ofIMD 16B or otherwise coupled to housing 60. In some examples, housingelectrode 58 is defined by an uninsulated portion of an outward facingportion of housing 60 of IMD 16B. Other division between insulated anduninsulated portions of housing 60 may be employed to define two or morehousing electrodes. In some examples, housing electrode 58 comprisessubstantially all of housing 60.

IMD 16B may sense electrical signals attendant to the depolarization andrepolarization of heart 12 via electrodes 40, 42, 44, 46, 48, 50, 58,62, 64, and 66. The electrical signals are conducted to IMD 16B from theelectrodes via conductors within the respective leads 18, 20, 22 or, inthe case of housing electrode 58, a conductor coupled to housingelectrode 58. IMD 16B may sense such electrical signals via any bipolarcombination of electrodes 40, 42, 44, 46, 48, 50, 58, 62, 64, and 66.Furthermore, any of the electrodes 40, 42, 44, 46, 48, 50, 58, 62, 64,and 66 may be used for unipolar sensing in combination with housingelectrode 58.

In some examples, IMD 16B delivers pacing pulses via bipolarcombinations of electrodes 40, 42, 44, 46, 48 and 50 to producedepolarization of cardiac tissue of heart 12. In some examples, IMD 16Bdelivers pacing pulses via any of electrodes 40, 42, 44, 46, 48 and 50in combination with housing electrode 58 in a unipolar configuration.

Furthermore, IMD 16B may deliver defibrillation pulses to heart 12 viaany combination of elongated electrodes 62, 64, 66, and housingelectrode 58. Electrodes 58, 62, 64, 66 may also be used to delivercardioversion pulses to heart 12. Electrodes 62, 64, 66 may befabricated from any suitable electrically conductive material, such as,but not limited to, platinum, platinum alloy or other materials known tobe usable in implantable defibrillation electrodes.

The configuration of the systems illustrated in FIGS. 1-4 are merelyexemplary. In other examples, a system may include percutaneous leads,epicardial leads and/or patch electrodes instead of or in addition tothe transvenous leads 18 and 22 illustrated in FIG. 2. Further, the IMDneed not be implanted within patient 14. In examples in which the IMD isnot implanted in a patient, the IMD may deliver defibrillation pulsesand other therapies to heart 12 via percutaneous leads that extendthrough the skin of patient 14 to a variety of positions within oroutside of heart 12.

In addition, in other examples, a system may include any suitable numberof leads coupled to IMD 16B, and each of the leads may extend to anylocation within or proximate to heart 12. For example, other examples ofsystems may include three transvenous leads located as illustrated inFIGS. 2 and 4, and an additional lead located within or proximate toleft atrium 36. Other examples of systems may include a single lead thatextends from IMD 16B into right atrium 26 or right ventricle 28, or twoleads that extend into a respective one of the right ventricle 26 andright atrium 26. Any electrodes located on these additional leads may beused in sensing and/or stimulation configurations.

FIG. 5 is a functional block diagram illustrating an exampleconfiguration of IMD 16, which may be IMD 16A of FIGS. 1 and 3 or IMD16B of FIGS. 2 and 4. In the example illustrated by FIG. 4, IMD 16includes a processor 80, memory 82, signal generator 84, electricalsensing module 86, telemetry module 88, system clock 90, reference clock92, clock calibrator 94A, and power source 98. Memory 82 may includecomputer-readable instructions that, when executed by processor 80,cause IMD 16 and processor 80 to perform various functions attributed toIMD 16 and processor 80 herein. Memory 82 may comprise acomputer-readable storage medium, including any volatile, non-volatile,magnetic, optical, or electrical media, such as a random access memory(RAM), read-only memory (ROM), non-volatile RAM (NVRAM),electrically-erasable programmable ROM (EEPROM), flash memory, or anyother digital or analog storage media.

Processor 80 may include any one or more of a microprocessor, acontroller, a digital signal processor (DSP), an application specificintegrated circuit (ASIC), a field-programmable gate array (FPGA), orequivalent discrete or integrated logic circuitry. In some examples,processor 80 may include multiple components, such as any combination ofone or more microprocessors, one or more controllers, one or more DSPs,one or more ASICs, or one or more FPGAs, as well as other discrete orintegrated logic circuitry. The functions attributed to processor 80 inthis disclosure may be embodied as software, firmware, hardware or anycombination thereof. IMD 16 also includes a sensing integrity module 90,as illustrated in FIG. 6, which may be implemented by processor 80,e.g., as a hardware component of processor 80, or a software componentexecuted by processor 80.

In the disclosed embodiments, the operation of the device according tothe invention is accomplished by the processor 80 as defined byinstructions stored in memory 82. For purposes of the disclosedinvention, the instruction set may correspond to the required sequenceof operations as set forth in Exhibit A, attached hereto.

Processor 80 controls signal generator 84 to deliver stimulation therapyto heart 12 according to operational parameters or programs, which maybe stored in memory 82. For example, processor 80 may control signalgenerator 84 to deliver electrical pulses with the amplitudes, pulsewidths, frequency, or electrode polarities specified by the selected oneor more therapy programs.

Signal generator 84, as well as electrical sensing module 86, iselectrically coupled to electrodes of IMD 16 and/or leads coupled to IMD16. In the example of leadless IMD 16A of FIG. 3, signal generator 84and electrical sensing module 86 are coupled to electrodes 72 and 74,e.g., via conductors disposed within housing 78 of leadless IMD 16A. Inexamples in which fixation mechanism 70 functions as an electrode,signal generator 84 and electrical sensing module 86 may also be coupledto fixation mechanism 70, e.g., via a conductor disposed within housing78 of leadless IMD 16A. In the example of IMD 16B of FIG. 2, signalgenerator 84 and electrical sensing module 86 are coupled to electrodes40, 42, 48, 50, 56 and 62via conductors of the respective lead 18 or 22,or, in the case of housing electrode 58, via an electrical conductordisposed within housing 60 of IMD 16B.

In the example illustrated in FIG. 4, signal generator 84 is configuredto generate and deliver electrical stimulation therapy to heart 12. Forexample, signal generator 84 may deliver pacing, cardioversion,defibrillation, and/or neurostimulation therapy via at least a subset ofthe available electrodes. In some examples, signal generator 84 deliversone or more of these types of stimulation in the form of electricalpulses. In other examples, signal generator 84 may deliver one or moreof these types of stimulation in the form of other signals, such as sinewaves, square waves, or other substantially continuous time signals.

Signal generator 84 may include a switch module and processor 80 may usethe switch module to select, e.g., via a data/address bus, which of theavailable electrodes are used to deliver stimulation signals, e.g.,pacing, cardioversion, defibrillation, and/or neurostimulation signals.The switch module may include a switch array, switch matrix,multiplexer, or any other type of switching device suitable toselectively couple a signal to selected electrodes.

Electrical sensing module 86 monitors signals from at least a subset ofthe available electrodes in order to monitor electrical activity ofheart 12. Electrical sensing module 86 may also include a switch moduleto select which of the available electrodes are used to sense the heartactivity. In some examples, processor 80 may select the electrodes thatfunction as sense electrodes, i.e., select the sensing configuration,via the switch module within electrical sensing module 86, e.g., byproviding signals via a data/address bus.

In some examples, electrical sensing module 86 includes multipledetection channels, each of which may comprise an amplifier. Eachsensing channel may detect electrical activity in respective chambers ofheart 12, and may be configured to detect either R-waves or P-waves. Insome examples, electrical sensing module 86 or processor 80 may includean analog-to-digital converter for digitizing the signal received from asensing channel for electrogram (EGM) signal processing by processor 80.In response to the signals from processor 80, the switch module withinelectrical sensing module 86 may couple the outputs from the selectedelectrodes to one of the detection channels or the analog-to-digitalconverter.

During pacing, escape interval counters maintained by processor 80 maybe reset upon sensing of R-waves and P-waves with respective detectionchannels of electrical sensing module 86. Signal generator 84 mayinclude pacer output circuits that are coupled, e.g., selectively by aswitching module, to any combination of the available electrodesappropriate for delivery of a bipolar or unipolar pacing pulse to one ormore of the chambers of heart 12. Processor 80 may control signalgenerator 84 to deliver a pacing pulse to a chamber upon expiration ofan escape interval. Processor 80 may reset the escape interval countersupon the generation of pacing pulses by signal generator 84, ordetection of an intrinsic depolarization in a chamber, and therebycontrol the basic timing of cardiac pacing functions. The escapeinterval counters may include P-P, V-V, RV-LV, A-V, A-RV, or A-LVinterval counters, as examples. The value of the count present in theescape interval counters when reset by sensed R-waves and P-waves may beused by processor 80 to measure the durations of R-R intervals, P-Pintervals, P-R intervals and R-P intervals. Processor 80 may use thecount in the interval counters to detect heart rate, such as an atrialrate or ventricular rate.

The processor 80 also stores records of the following values in memory:a) cumulative lifetime brady pace counter; b)cumulative lifetime bradysense counter; c) programmed ventricular amplitude; and d) programmedventricular pulse width. These values are used to determine theestimated remaining life of the pacemaker as described below.

Telemetry module 88 includes any suitable hardware, firmware, softwareor any combination thereof for communicating with another device, suchas programmer 24 (FIGS. 1 and 2). Under the control of processor 80,telemetry module 88 may receive downlink telemetry from and send uplinktelemetry to programmer 24 with the aid of an antenna, which may beinternal and/or external. Processor 80 may provide the data to beuplinked to programmer 24 and receive downlinked data from programmer 24via an address/data bus. In some examples, telemetry module 88 mayprovide received data to processor 80 via a multiplexer.

The clocking system of IMD 16 includes system clock 90, reference clock92, and clock calibrator 94A. Each of the clocks described hereincomprise oscillators that may operate at different frequencies withdifferent accuracies and different power requirements. IMD 16 mayrequire an extremely small housing form factor, especially in the caseof leadless IMD 16A of FIGS. 1 and 3. For example, leadless IMD 16 mayhave a form factor of less than 1 cubic centimeter. Due to the smallform factor requirements, IMD 16 may only be able to accommodate a smallbattery canister such that current drain within IMD 16 must by extremelylow. One aspect of reducing power in IMD 16 is to minimize current drainby the clocking system.

A detailed description of the use of the clocking system to reduce powerconsumption is set forth in US Patent Publication No. US 20120109259 A1,incorporated herein by reference in its entirety

FIG. 6 is a functional block diagram of an example configuration ofprogrammer 24. As shown in FIG. 12, programmer 24 includes processor140, memory 142, user interface 144, telemetry module 146, and powersource 148. Programmer 24 may be a dedicated hardware device withdedicated software for programming of IMD 16. Alternatively, programmer24 may be an off-the-shelf computing device running an application thatenables programmer 24 to program IMD 16. In other examples, programmer24 may be used to program IMD 16 of FIG. 7 in a substantially similarmanner as IMD 16 of FIG. 6.

A user may use programmer 24 to select therapy programs (e.g., sets ofstimulation parameters), generate new therapy programs, or modifytherapy programs for IMD 16. The clinician may interact with programmer24 via user interface 144, which may include a display to present agraphical user interface to a user, and a keypad or another mechanismfor receiving input from a user.

Processor 140 can take the form one or more microprocessors, DSPs,ASICs, FPGAs, programmable logic circuitry, or the like, and thefunctions attributed to processor 140 in this disclosure may be embodiedas hardware, firmware, software or any combination thereof. Memory 142may store instructions and information that cause processor 140 toprovide the functionality ascribed to programmer 24 in this disclosure.Memory 142 may include any fixed or removable magnetic, optical, orelectrical media, such as RAM, ROM, CD-ROM, hard or floppy magneticdisks, EEPROM, or the like. Memory 142 may also include a removablememory portion that may be used to provide memory updates or increasesin memory capacities. A removable memory may also allow patient data tobe easily transferred to another computing device, or to be removedbefore programmer 24 is used to program therapy for another patient.Memory 142 may also store information that controls therapy delivery byIMD 16, such as stimulation parameter values.

Programmer 24 may communicate wirelessly with IMD 16, such as using RFcommunication or proximal inductive interaction. This wirelesscommunication is possible through the use of telemetry module 146, whichmay be coupled to an internal antenna or an external antenna. Anexternal antenna that is coupled to programmer 24 may correspond to theprogramming head that may be placed over heart 12, as described abovewith reference to FIG. 1. Telemetry module 146 may be similar totelemetry module 88 of IMD 16 (FIG. 6).

Telemetry module 146 may also be configured to communicate with anothercomputing device via wireless communication techniques, or directcommunication through a wired connection. Examples of local wirelesscommunication techniques that may be employed to facilitatecommunication between programmer 24 and another computing device includeRF communication according to the 802.11 or Bluetooth specificationsets, infrared communication, e.g., according to the IrDA standard, orother standard or proprietary telemetry protocols. In this manner, otherexternal devices may be capable of communicating with programmer 24without needing to establish a secure wireless connection. An additionalcomputing device in communication with programmer 24 may be a networkeddevice such as a server capable of processing information retrieved fromIMD 16.

FIG. 7 is a block diagram illustrating an example system that includesan external device, such as a server 204, and one or more computingdevices 210A-210N, that are coupled to the IMD 16 and programmer 24(shown in FIGS. 1 and 2) via a network 202. In other examples, thesystem of FIG. 13 may include IMD 116 of FIG. 7 in a substantiallysimilar manner as IMD 16 of FIG. 6.

In this example, IMD 16 may use its telemetry module 88 to communicatewith programmer 24 via a first wireless connection, and to communicationwith an access point 200 via a second wireless connection. In theexample of FIG. 13, access point 200, programmer 24, server 204, andcomputing devices 210A-210N are interconnected, and able to communicatewith each other, through network 202. In some cases, one or more ofaccess point 200, programmer 24, server 204, and computing devices210A-210N may be coupled to network 202 through one or more wirelessconnections. IMD 16, programmer 24, server 204, and computing devices210A-210N may each comprise one or more processors, such as one or moremicroprocessors, DSPs, ASICs, FPGAs, programmable logic circuitry, orthe like, that may perform various functions and operations, such asthose described herein.

Access point 200 may comprise a device that connects to network 202 viaany of a variety of connections, such as telephone dial-up, digitalsubscriber line (DSL), or cable modem connections. In other examples,access point 200 may be coupled to network 202 through different formsof connections, including wired or wireless connections. In someexamples, access point 200 may be co-located with patient 14 and maycomprise one or more programming units and/or computing devices (e.g.,one or more monitoring units) that may perform various functions andoperations described herein. For example, access point 200 may include ahome-monitoring unit that is co-located with patient 14 and that maymonitor the activity of IMD 16. In some examples, server 204 orcomputing devices 210 may control or perform any of the variousfunctions or operations described herein.

In some cases, server 204 may be configured to provide a secure storagesite for data that has been collected from IMD 16 and/or programmer 24.Network 202 may comprise a local area network, wide area network, orglobal network, such as the Internet. In some cases, programmer 24 orserver 206 may assemble data in web pages or other documents for viewingby trained professionals, such as clinicians, via viewing terminalsassociated with computing devices 210A-210N. The illustrated system ofFIG. 13 may be implemented, in some aspects, with general networktechnology and functionality similar to that provided by the MedtronicCareLink® Network developed by Medtronic, Inc., of Minneapolis, Minn.

In one or more examples, the functions described above may beimplemented in hardware, software, firmware, or any combination thereof.If implemented in software, the functions may be stored on ortransmitted over as one or more instructions or code on acomputer-readable medium. Computer-readable media may include computerdata storage media or communication media including any medium thatfacilitates transfer of a computer program from one place to another.Data storage media may be any available media that can be accessed byone or more computers or one or more processors to retrieveinstructions, code and/or data structures for implementation of thetechniques described in this disclosure. By way of example, and notlimitation, such computer-readable media can comprise RAM, ROM, EEPROM,CD-ROM or other optical disk storage, magnetic disk storage, or othermagnetic storage devices, flash memory, or any other medium that can beused to carry or store desired program code in the form of instructionsor data structures and that can be accessed by a computer. Also, anyconnection is properly termed a computer-readable medium. For example,if the software is transmitted from a website, server, or other remotesource using a coaxial cable, fiber optic cable, twisted pair, digitalsubscriber line (DSL), or wireless technologies such as infrared, radio,and microwave, then the coaxial cable, fiber optic cable, twisted pair,DSL, or wireless technologies such as infrared, radio, and microwave areincluded in the definition of medium. Disk and disc, as used herein,includes compact disc (CD), laser disc, optical disc, digital versatiledisc (DVD), floppy disk and blu-ray disc where disks usually reproducedata magnetically, while discs reproduce data optically with lasers.Combinations of the above should also be included within the scope ofcomputer-readable media.

The code may be executed by one or more processors, such as one or moredigital signal processors (DSPs), general purpose microprocessors,application specific integrated circuits (ASICs), field programmablelogic arrays (FPGAs), or other equivalent integrated or discrete logiccircuitry. Accordingly, the term “processor,” as used herein may referto any of the foregoing structure or any other structure suitable forimplementation of the techniques described herein. In addition, in someaspects, the functionality described herein may be provided withindedicated hardware and/or software modules. Also, the techniques couldbe fully implemented in one or more circuits or logic elements.

For purposes of understanding the invention the following definitionswill be helpful:

BOS-Beginning of Service

When an individual IPG is first released by the manufacturer as fit forplacing on the market.

EOS-End of Service

When the Prolonged Service Period (PSP) has elapsed and performance todesign specifications cannot be assured.

PSP-Prolonged Service Period

Period beyond the Recommended Replacement Time (RRT) during which theIPG continues to function as defined by the manufacturer to prolongbasic bradyarrhythmia pacing.

PSL-Projected Service Life

Period from the implantation of the IPG to the Recommended ReplacementTime (RRT) under defined conditions.

RRT-Recommended Replacement Time

Time when the power source indicator reaches the value set by themanufacturer of the IPG for its recommended replacement. This indicatesentry into the Prolonged Service Period (PSP).

ERI-Elective Replacement Indicator

ERI is not a CENELEC definition. ERI is a secondary indicator which isintended to inform the user that there is less than 90 days of deviceservice remaining.

Pre-RRT-Pre-Recommended Replacement Time

Pre-RRT is not a CENELEC definition, and it is not shown to the user.Pre-RRT is an indicator that the battery voltage is transitioning fromthe first plateau to the second plateau.

The occurrences of these events are stored in memory 82 and may becommunicated to the user by means of telemetry to an associated devicesuch as the programmer of FIG. 6 as described above. Occurrence of theseevents may also be communicated remotely using the system of FIG. 7 asdescribed above

The inter-relation of the above-defined events is illustrated in FIG. 8.

The times of occurrences of these defined events relative to anexemplary battery discharge curve are illustrated in FIG. 9. The firstshelf or plateau extends for a certain time period until the batterydischarge curve quickly decreases while the second shelf or plateauextends a shorter time period, as shown in FIG. 9.

FIG. 10 sets forth an exemplary look-up table relating pacing pulsewith, pacing pulse programmed amplitude and pacing percentage toestimated battery life (Remaining Longevity Duration Value) in days.This look-up table will of course be different for each device in eachtype of device in which the invention is employed, depending on thecurrent drain, battery capacity, battery chemistry, etc. of each devicetype.

As an additional option, the static current drain for each individualdevice of a given type could be measured at production and thecorresponding look up table for that device could be individuallycalculated and then written it to flash memory in the device. This wouldallow the longevity for each individual device to be maximized based onits own unique current drain.

Additionally, while the look-up table of FIG. 10 is based uponamplitude, pulse width and percentage of pacing, in alternativeembodiments, additional factors such as pacing impedance could also beemployed to provide a more accurate prediction of battery life.

Operation of the device generally according to the invention isaccording to the following set of rules as set forth below. These rulesmay be embodied as a corresponding instruction set stored in memory 82,executed by processor 80.

RRT Indicator

The device records the time/date that RRT occurred. Once a number ofconsecutive daily battery measurements are at or below a Pre-RRT voltagetrip threshold, as discussed below, a configurable delay timer isstarted as indicated at “A” below. The RRT indicator is set once thattimer expires or the battery voltage become less than or equal to a RRTvoltage trip threshold for a programmable number of consecutive days.

More specifically, the device sets the RRT indicator and records theReal Time Clock as a RRT Battery Voltage Detected Timestamp the firsttime either of the following conditions occurs:

A. Remaining Longevity Duration determined as discussed below minus thenumber of days since Pre-RRT Battery Voltage was detected is less thanor equal to 180 days.

B. Three (3) consecutive daily Battery Voltage Measurements are lessthan or equal to Low Battery Voltage RRT Threshold where Holter Mode wasnot active during any of the 3 days.

PRE-RRT Indicator

The first time three (3) consecutive daily Battery Voltage Measurementsare less than or equal to a Pre-RRT voltage trip threshold where HolterMode was not active during any of the 3 days, the device sets a Pre-RRTBattery Voltage Detected flag and records the Real Time Clock in aPre-RRT Battery Voltage Detected Timestamp.

ERI Indictor

The device sets the ERI indicator and record the Real Time Clock in ERIBattery Voltage Detected Timestamp the first time either of thefollowing conditions occurs:

A. Remaining Longevity Duration calculated as discussed below minus thenumber of days since Pre-RRT Battery Voltage was detected is less thanor equal to 90 days.

B. Three (3) consecutive daily battery voltage measurements are lessthan or equal to Low Battery Voltage ERI Threshold where Holter Mode wasnot active during any of the 3 days.

EOS Indicator

The device sets the EOS indicator and record the real time clock as anEOS Battery Voltage Detected Timestamp under either of the followingconditions:

A. Greater than or equal to (≧)120 days have elapsed since the deviceset the ERI indicator and/or a power on reset (POR) occurs or

B. Three consecutive battery voltage measurements are less than or equalto Low Battery Voltage EOS Threshold where the holter mode was notactive during any of the three days.

As a result, the RRT, ERI and EOS indicators as discussed above may allbe triggered responsive to a determined number of days elapsing sincethe Pre-RRT voltage was detected. This determined number of days sincePre-RRT was detected is based upon the Remaining Longevity Duration asinitially calculated and then re-calculated as discussed below.

Remaining Longevity Duration—Initial Value

Responsive to Pre-RRT Battery Voltage being detected as above, thedevice:

A. Determines the pacing percentage (cumulative lifetime brady pacecounter/(cumulative lifetime brady pace counter+cumulative lifetimebrady sense counter)); and

B. Uses the pacing percentage, Programmed Ventricular Amplitude andProgrammed Ventricular Pulse Width to set the Remaining LongevityDuration in days from Pre-RRT per FIG. 10 (Remaining Longevity DurationValue)

Remaining Longevity Duration Recalculation

After Pre-RRT detected as above and before ERI has been reached, eachday at midnight (prior to starting any Temporary Operation scheduled tostart at midnight), if:

A. The Telemetry State is Disconnect, AND

B. The Emergency VVI Timer is not active, AND

C. No Temporary Operation is in progress,

then the device:

A. Determines the pacing percentage (cumulative lifetime brady pacecounter/(cumulative lifetime brady pace counter+cumulative lifetimebrady sense counter)), AND

B. Uses the pacing percentage, Programmed Ventricular Amplitude andProgrammed Ventricular Pulse Width to determine the Potential RemainingLongevity Duration per FIG. 10 in days from Pre-RRT.

C. Resets Remaining Longevity Duration to the MIN(Potential RemainingLongevity Duration, previous Remaining Longevity Duration).

Recalculation of Remaining Device Longevity therefore can only maintainor reduce amount of time remaining before triggering of the RRT/ERI/EOSindicators. In other words, once established, Remaining LongevityDuration may be only be reduced and this reduction means that the numberof days between Pre-RRT and RRT/ERI/EOS is also reduced). Therefore, itis possible that once a change in Remaining Longevity Duration isidentified, the number of days since Pre-RRT may already be larger thanthe newly changed Remaining Longevity Duration. In this case, RRT willbe triggered immediately.

Mode Change at Eri

When ERI is detected, if the device is in a pacing mode, the device willchange to standard ERI settings of WI pacing at 65 bpm.

The external instrument (programmer) may re-program the parameters afterthe device has changed to the ERI values.

Eri Parameter Change

When ERI is detected and the programmed Brady Pacing Mode OOO (i.e. noshock, no pacing, no anti-Bradycardia pacing of a chamber, according tothe NBG Pacemaker Code) or OVO (i.e. no shock, sensing of the ventriclesuch as the RV, no anti-Bradycardia pacing of a chamber), the deviceshall change the brady parameter values as follows:

A. The programmed Brady Pacing Mode shall be set to VVI

B. The programmed Brady Lower Rate shall be set to 65 BPM

C. The programmed Brady Hysteresis Enable shall be set to OFF.Hysteresis is disabled to ensure that paces are delivered at 65 BPM.

The usable life in years for the IMD 16A,B can be affected by programmedsettings or parameters used during the operation of the IMD 16A,B.Exemplary programmed parameters that may be used to affect the totalcurrent drain on the IMD 16A,16B include pacing amplitude, pacing pulsewidth, pacing impedance, percent (%) pacing, pacing rate, time in atrialtachycardia/atrial fibrillation (AT/AF), and EGM pre-storage.

Total current drain on IMD 16A, 16B, calculated by the programmer, isdetermined through estimating current drain caused by individualprogrammed settings by the programmer. For example, the current drainrelated to the pacing rate can be estimated by multiplying the pacingrate with the amount of time that tissue is paced. The programmer thencalculates the total current drain by adding current drain caused byeach individual programmed setting programmed for operation in IMD16A,B.By estimating the total current drain on IMD 16A,B, a determination canbe made as to whether the device is in a relatively high current drainstate (e.g. >20 uA), a medium current drain state (e.g. between 15-20uA) or a relatively low current drain state (e.g. <15 uA).

The time between pre-RRT and RRT depends on current drain estimate. Ifthe estimated current drain is high, the time from pre-RRT to RRT willbe relatively short. If the estimated current drain is low, the timefrom pre-RRT to RRT will be relatively long.

A pre-recommended replacement time (pre-RRT) condition, established incomputer instructions, is an indicator that the battery voltage istransitioning from a first plateau to the second plateau, as shown inFIG. 11.

In some battery chemistries, the trip points occur on “plateaus” in thebattery curve, making voltage/impedance may not be as reliable way inwhich to predict replacement. In this case, the number of days countersare the primary means of changing longevity states, with batteryvoltages as a backup only.

Device battery life is extremely variable based on implantable medicaldevice parameters such as pacing impedance, pacing amplitude, pacingpulse width, pacing rate and pacing percentage. In the case of somedevices, the battery is such that several of the longevity stateswitches occur during a battery voltage plateau. Changing longevitystates at the right time is critical to providing the CommissionEuropénne de Normalisation Électrique (CENELEC) required number of daysbetween longevity states while also maximizing the device longevity. Theinvention is particularly beneficial in this context.

The pre-RRT condition occurs at a pre-specified battery voltage beforereaching a plateau of about 2.625 volts. In one or more embodiments, thepre-RRT condition typically must be consistently detected over apre-specified period of time (e.g. three (3) consecutive days etc.)before being deemed present in the device.

The graphical user interface of the programmer or other external devicecan be configured to display data such as the pre-RRT and the precisedates in which the battery or device must be replaced. For example, the“remaining longevity” estimate will display “RRT will occur in 180 days(on Jun. 1, 2020).” In one or more other embodiments, RRT occurs at afixed time after a pre-RRT condition has been detected consistently overa pre-specified time period. The pre-specified time period could be, forexample, up to three consecutive days. In one or more other embodiments,when a pre-RRT is detected less than 5 years from the date the IMD wasimplanted, the graphical user interface can be configured to display theappropriate calendar date or days to RRT. For example, the graphicaluser interface on the programmer can provide the number of days “ERIwill occur in 90 days (on Sep. 1, 2020).” In exemplary graphical userinterface is presented in FIG. 12, which shows the remaining longevityand provides a date of 20 Apr. 2012. Additionally, RR is stated to occurin 180 days of 20 Oct. 2012. The battery voltage is detected at 2.62 Von20 Apr. 2012.

Current drain is current drawn away from a voltage source by a load suchas performing day-to-day operation of the IMD's electronic circuits.Electronic processing, obtaining measurements for diagnostic data,implementing algorithms, and other functions require a relatively largeamount of energy. In order to increase the life of the battery and, inturn, the life of the IMD16A,B, it is desirable to increase the timeperiod between the point of pre-RRT threshold level (i.e. 2.625 volts)and RRT, denoted as “A” on FIG. 11, provided that the CENELEC conditionof at least 180 days exists between the RRT and EOS (denoted as “B onFIG. 11) is met.

First Algorithm

In order to satisfy the CENELEC condition of 180 days existing betweenthe RRT and EOS and the other condition of extending the time period of“A” can be set to different values dependent upon the amount ofestimated current drain exhibited by the IMD 16A, B. For example, “A”can be set to a first time value (i.e. 90 days etc.) provided theestimated current drain is greater than a first current value (i.e. 20microamperes). If the static current drain is between a second currentvalue (i.e. 15-20 microamperes), “A” is set to a second time value (i.e.210 days) instead of 90 days. If the current drain is less than a thirdcurrent value (i.e. 15 microamperes), the “A” is set to a third timevalue (i.e. 360 days).

Second Algorithm

To implement the second algorithm, the pre-RRT threshold level is againset to 2.625V. In one or more embodiments, the RRT=pre-RRT+90 days ifthe time from implant to the time in which pre-RRT threshold is detectedoccurs at a time period less than 5 years from the implant date. Inanother embodiment, the RRT=pre-RRT+180 days if the time from implant tothe time in which pre-RRT threshold is detected is within the range of5-7 years from the implant date. In yet another embodiment, theRRT=pre-RRT+360 days if the time from implant to the time that pre-RRTthreshold is detected is greater than 7 years. In one or moreembodiments, the RRT=pre-RRT-180 days if the time from implant to thetime in which pre-RRT threshold is detected is within the range of 5-7years from the implant date.

In one or more other embodiments, if any pacing amplitude (e.g. atrial(A)/right ventricular “RV”/left atrial “(LA”)) is greater than 5V, orbecomes greater than 5V, then 90 days to RRT can be configured to bedisplayed the graphical user interface of the programmer. In one or moreother embodiments, if battery voltage is less than 2.57V, thenimmediately trigger RRT. In addition to the conditions described herein,CENELEC requires compliance with ERI=RRT+90 days and EOS=ERI+90 days.

While the disclosed embodiment takes the form of a pacemaker, theinvention is readily applicable to other stimulator types includingimplantable neuro-stimulators, and implantable cardioverters or in otherimplantable devices wherein battery drain may be variable over time asconditions of device use change. Dual chamber ICDs, pacemakers or triplechamber devices CRT-P devices (e.g. Medtronic VIVA™ CRT-P Protecta™ XTDR, Consulta™ CRT-P, Syncra™ CRT-P etc.) use different programmedfeatures. For example, the dual chamber IMDs such as Advisa™ DR, etc.can be configured to operate up to 11.0 years of usable life.

Exemplary embodiments are as follows:

-   Embodiment 1 is a method of determining estimated remaining    longevity for an implantable stimulator having a power source,    comprising:

using a programmer processor to acquire from the implantable stimulatora signal comprising data associated with the power source in theimplantable stimulator and a date in which the stimulator was implanted;

using the programmer processor and the data to determine whether apre-recommended replacement time threshold (pre-RRT) has been attainedfor replacing the implantable stimulator;

using the programmer processor to select an equation in which tocalculate a recommended replacement time (RRT), the equation is selectedin response to determining a time period that extends from the date inwhich the stimulator was implanted until a date in which the pre-RRT isattained; and using the programmer processor to generate a notificationto a user as to the RRT.

-   Embodiment 2 is the method of embodiment 1 wherein the notification    is displayed on a graphical user interface of the programmer, the    notification includes a date as to the remaining longevity.-   Embodiment 3 is the method of any of embodiments 1-2 wherein the    data comprising one of voltage data and current data.-   Embodiment 4 is the method of any of embodiments 1-3 wherein the    equation for RRT=pre-RRT+90 days if the time period is less than 5    years from the implant date.-   Embodiment 5 is the method of any of embodiments 1-4 wherein the    equation for RRT=pre-RRT+180 days if the time period is in the range    of about 5 to about 7 years from the implant date.-   Embodiment 6 is the method of any of embodiments 1-5 wherein the    equation for RRT=pre-RRT+360 days if the time period is greater than    7 years from the implant date.-   Embodiment 7 is the method of any of embodiments 1-6 wherein the    implantable stimulator changes a mode of operation in response to    current drain.-   Embodiment 8 is an apparatus for determining estimated remaining    longevity for an implantable stimulator having a power source,    comprising:

means for employing the implantable stimulator to send a signal to theprogrammer processor, the signal comprising voltage data associated withthe power source in the implantable stimulator and a date in which thestimulator was implanted;

means for using the programmer processor and the voltage data todetermine whether a pre-recommended replacement time threshold (pre-RRT)has been attained for replacing the implantable stimulator;

means for using the programmer processor to select an equation in whichto calculate a recommended replacement time (RRT), the equation isselected in response to determining a time period that extends from thedate in which the stimulator was implanted until a date in which thepre-RRT is attained; and

means for using the programmer processor to generate a notification to auser as to the RRT.

-   Embodiment 9 is the apparatus of embodiment 8 further comprising:

means for displaying on a graphical user interface a date as to theremaining longevity.

-   Embodiment 10 is the apparatus according to embodiment 8 wherein the    equation for RRT=pre-RRT+90 days if the time period is less than 5    years from the implant date.-   Embodiment 11 is the apparatus according to any of embodiments 8-10    wherein the equation for RRT=pre-RRT+180 days if the time period is    in the range of about 5 to about 7 years from the implant date.-   Embodiment 12 is the apparatus according to any of embodiments 8-11    wherein the equation for RRT=pre-RRT+360 days if the time period is    greater than 7 years from the implant date.-   Embodiment 13 is the apparatus according to any of embodiments    8-12wherein the implantable stimulator comprises a cardiac    resynchronization therapy pacemaker.-   Embodiment 14 is an apparatus for determining estimated remaining    longevity for an implantable stimulator comprising a power source,    comprising:

means for employing the implanted stimulator to signal a programmer, thesignal comprising current drain data associated with the power source;

means for the programmer to determine a current drain associated withthe power source;

means for employing programmer to select a recommended replacement timeof the stimulator by using the current drain data.

-   Embodiment 15 is the apparatus according to embodiment 14 further    comprising:

means for displaying on a graphical user interface a date as to theremaining longevity, wherein RRT is set to a predetermined equation inresponse to determining a time from implant to a time in which pre-RRTthreshold is detected.

-   Embodiment 16 is a method of determining estimated remaining    longevity for an implantable stimulator having a power source,    comprising:

employing the implantable stimulator to signal a programmer having aprocessor;

employing the programmer processor to acquire current drain data fromthe signal;

employing the programmer processor to set the recommended replacementtime (RRT) a pre-calculated numbers of days in response to the currentdrain data, the RRT set to one of a first time period, a second timeperiod and a third time period.

-   Embodiment 17 is the method according to embodiment 16 further    comprising:

displaying on a graphical user interface a date as to the remaininglongevity.

-   Embodiment 18 is a method according to any of embodiments 16-17    wherein the device usage parameters that results in total current    drain data comprise pacing pulse amplitude, pacing pulse duration    percentage of pacing, pacing pulse width, pacing impedance, pacing    rate, time in atrial tachycardia/atrial fribrillation (AT/AF), and    EGM pre-storage.-   Embodiment 19 is a method according to embodiments 16-17 wherein the    determined RRT comprising the first, second and third defined time    periods comprises 90 days, 210 days, and 360 days, respectively.-   Embodiment 20 is a method according to any of embodiments 17-19    wherein the determined the first, second and third defined time    periods are based upon a first current threshold, second current    threshold, and third current threshold.-   Embodiment 21 is a method according to any of the embodiments 16-20    wherein the determination of remaining device longevity comprises a    second defined time period in response to device current drain    falling within a defined second current threshold.-   Embodiment 22 is a method according to any of embodiments 16-21    wherein the determination of remaining device longevity is performed    initially in response to device current drain falling below a    defined third current threshold.-   Embodiment 23 is a method according to any of embodiments 16-22    wherein the indicator states correspond to one or more of    pre-recommended replacement Time (pre-RRT) Recommended Replacement    Time (RRT), Elective Replacement Indicator (ERI) or End of Service    (EOS).-   Embodiment 24 is a method according to embodiment 14 wherein the    first current threshold is greater than 20 microamperes.

Embodiment 25 is method according to embodiment 14 wherein the secondcurrent threshold is between 15-20 microamperes.

Embodiment 26 is a method according to embodiment 14 wherein the thirdcurrent threshold is less than 15 microamperes.

-   Embodiment 27 is a non-transitory programming medium comprising    instructions for determining estimated remaining longevity for an    implantable stimulator, comprising:

instructions for using a programmer processor to acquire from theimplantable stimulator a signal comprising data associated with thepower source in the implantable stimulator and a date in which thestimulator was implanted;

instructions for using the programmer processor and the data todetermine whether a pre-recommended replacement time threshold (pre-RRT)has been attained for replacing the implantable stimulator;

instructions for using the programmer processor to select an equation inwhich to calculate a recommended replacement time (RRT), the equation isselected in response to determining a time period that extends from thedate in which the stimulator was implanted until a date in which thepre-RRT is attained; and

instructions for using the programmer processor to generate anotification to a user as to the RRT.

-   Embodiment 28 is an apparatus for determining estimated remaining    longevity for an implantable stimulator having a power source and    processor, comprising:

means for employing the processor to acquire data associated with thepower source in the implantable stimulator and a date in which thestimulator was implanted;

means for using the processor and the voltage data to determine whethera pre-recommended replacement time threshold (pre-RRT) has been attainedfor replacing the implantable stimulator;

means for using the processor to select an equation in which tocalculate a recommended replacement time (RRT), the equation is selectedin response to determining a time period that extends from the date inwhich the stimulator was implanted until a date in which the pre-RRT isattained; and

means for using the processor to generate a notification to a user as tothe RRT.

Further, while the invention is especially useful in the context ofleadless implantable devices, it is correspondingly beneficial in thecontext of devices including one or more leads as discussed above.Various examples of the disclosure have been described. These and otherexamples are within the scope of the following claims.

1. A method of determining estimated remaining longevity for animplantable stimulator having a power source, comprising: using aprogrammer processor to acquire from the implantable stimulator a signalcomprising data associated with the power source in the implantablestimulator and a date in which the stimulator was implanted; using theprogrammer processor and the data to determine whether a pre-recommendedreplacement time threshold (pre-RRT) has been attained for replacing theimplantable stimulator; using the programmer processor to select anequation in which to calculate a recommended replacement time (RRT), theequation is selected in response to determining a time period thatextends from the date in which the stimulator was implanted until a datein which the pre-RRT is attained; and using the programmer processor togenerate a notification to a user as to the RRT.
 2. The method of claim1 wherein the notification is displayed on a graphical user interface ofthe programmer, the notification includes a date as to the remaininglongevity.
 3. The method of claim 1 wherein the data comprises one ofvoltage data and current data.
 4. The method according to claim 1wherein the equation for RRT=pre-RRT+90 days if the time period is lessthan 5 years from the implant date.
 5. The method according to claim 1wherein the equation for RRT=pre-RRT+180 days if the time period is inthe range of about 5 to about 7 years from the implant date.
 6. Themethod according to claim 1 wherein the equation for RRT=pre-RRT+360days if the time period is greater than 7 years from the implant date.7. The method according to claim 1 wherein the implantable stimulatorchanges a mode of operation in response to current drain.
 8. Anapparatus for determining estimated remaining longevity for animplantable stimulator having a power source, comprising: means foremploying the implantable stimulator to send a signal to a programmerprocessor, the signal comprising data associated with the power sourcein the implantable stimulator and a date in which the stimulator wasimplanted; means for using the programmer processor and the data todetermine whether a pre-recommended replacement time threshold (pre-RRT)has been attained for replacing the implantable stimulator; means forusing the programmer processor to select an equation in which tocalculate a recommended replacement time (RRT), the equation is selectedin response to determining a time period that extends from the date inwhich the stimulator was implanted until a date in which the pre-RRT isattained; and means for using the programmer processor to generate anotification to a user as to the RRT.
 9. The apparatus according toclaim 8 further comprising: means for displaying on a graphical userinterface a date as to the remaining longevity.
 10. The apparatusaccording to claim 8 wherein the equation for RRT=pre-RRT+90 days if thetime period is less than 5 years from the implant date.
 11. Theapparatus according to claim 8 wherein the equation for RRT=pre-RRT+180days if the time period is in the range of about 5 to about 7 years fromthe implant date.
 12. The apparatus according to claim 8 wherein theequation for RRT=pre-RRT+360 days if the time period is greater than 7years from the implant date.
 13. The apparatus of claim 8 wherein theimplantable stimulator comprises a cardiac resynchronization therapypacemaker.
 14. An apparatus for determining estimated remaininglongevity for a cardiac resynchronization therapy pacemaker comprising apower source, comprising: means for employing the pacemaker to signal aprogrammer, the signal comprising current drain data associated with thepower source; means for employing the programmer to compare the currentdrain data to a current threshold; and means for employing theprogrammer to select a recommended replacement time of the pacemaker byusing the current drain data, the current data associated withrecommended replacement time.
 15. The apparatus according to claim 14further comprising: means for displaying on a graphical user interface adate as to the remaining longevity.
 16. A method of determiningestimated remaining longevity for an implantable cardiacresynchronization therapy pacemaker having a power source, comprising:employing the pacemaker to signal a programmer, the programmer having aprocessor; employing the programmer processor to acquire current draindata from the signal; employing the programmer processor to set therecommended replacement time (RRT) a pre-specified time period inresponse to the current drain data compared to a set of current datathresholds.
 17. The method according to claim 16 further comprising:displaying on a graphical user interface a date as to the remaininglongevity.
 18. A method according to claim 16 wherein the device usageparameters that results in total current drain data comprise pacingpulse amplitude, pacing pulse duration percentage of pacing, pacingpulse width, pacing impedance, pacing rate, time in atrialtachycardia/atrial fribrillation (AT/AF), and EGM pre-storage.
 19. Amethod according to claim 17 wherein the pre-specified time period isone of first, second and third time periods comprising 90 days, 210days, and 360 days, respectively.
 20. A method according to of claim 19wherein the determined the first, second and third time periods arebased upon a set of current data thresholds, the set of current datathresholds comprising a first current threshold, a second currentthreshold, and a third current threshold.
 21. A method according toclaim 16 wherein the determination of remaining device longevitycomprises a second defined time period in response to device currentdrain falling within a defined second current threshold.
 22. A methodaccording to claim 16 wherein the determination of remaining devicelongevity is performed initially in response to device current drainfalling below a defined third current threshold.
 23. A method accordingto claim 14 wherein the first current threshold is greater than about 20microamperes.
 24. A method according to claim 14 wherein the secondcurrent threshold is between about 15 microamperes and about 20microamperes.
 25. A method according to claim 14 wherein the thirdcurrent threshold is less than about 15 microamperes.
 26. Anon-transitory programming medium comprising instructions fordetermining estimated remaining longevity for an implantable stimulator,comprising: instructions for using a programmer processor to acquirefrom the implantable stimulator a signal comprising data associated withthe power source in the implantable stimulator and a date in which thestimulator was implanted; instructions for using the programmerprocessor and the data to determine whether a pre-recommendedreplacement time threshold (pre-RRT) has been attained for replacing theimplantable stimulator; instructions for using the programmer processorto select an equation in which to calculate a recommended replacementtime (RRT), the equation is selected in response to determining a timeperiod that extends from the date in which the stimulator was implanteduntil a date in which the pre-RRT is attained; and instructions forusing the programmer processor to generate a notification to a user asto the RRT.
 27. An apparatus for determining estimated remaininglongevity for an implantable stimulator having a power source andprocessor, comprising: means for employing the processor to acquire dataassociated with the power source in the implantable stimulator and adate in which the stimulator was implanted; means for using theprocessor and the voltage data to determine whether a pre-recommendedreplacement time threshold (pre-RRT) has been attained for replacing theimplantable stimulator; means for using the processor to select anequation in which to calculate a recommended replacement time (RRT), theequation is selected in response to determining a time period thatextends from the date in which the stimulator was implanted until a datein which the pre-RRT is attained; and means for using the processor togenerate a notification to a user as to the RRT.